[SOLVED] How to get the lowest/smallest local IP?

yaplej · 10-07-2009, 04:56 PM

Hello,

I need to use the lowest/smallest IP address of the host in my module. Is there an easy way to get a list of the current IP addresses?

Thanks.

yaplej · 10-08-2009, 12:37 PM

Found some code that supposedly does does this, but have not been able to get it to return the correct address.

Code:

/* eth0 to __u32 IP address */
static inline __u32
getlocalIP(void){
	struct net_device *device;
	struct in_device *in_dev;
	struct in_ifaddr *if_addr;
	char dev_name[20];
	__u8 *addr;

	sprintf(dev_name,"eth%d",0);
	device = dev_get_by_name(dev_name);
	in_dev = (struct in_device *)device->ip_ptr;
	if_addr = in_dev->ifa_list;

	addr = (char *)&if_addr->ifa_local;
	
	printk(KERN_ALERT "Eth0 IP: %lu.",
	(unsigned int long)addr);
	
	return (__u32)addr;
}

yaplej · 10-08-2009, 01:17 PM

Got it working.

Code:

/* eth0 to __u32 IP address */
static inline __u32
getlocalIP(void){
	struct net_device *device;
	struct in_device *in_dev;
	struct in_ifaddr *if_addr;
	char dev_name[20];
	__u32 localIP;
	__u8 *addr;
	
	localIP = 0;

	sprintf(dev_name,"eth%d",0);
	device = dev_get_by_name(dev_name);
	in_dev = (struct in_device *)device->ip_ptr;
	if_addr = in_dev->ifa_list;
	
	addr = (char *)&if_addr->ifa_local;

	localIP += (addr[0] << 24);
	localIP += (addr[1] << 16);
	localIP += (addr[2] << 8);
	localIP += addr[3];

	return localIP;
}